In a large skillet, brown ground beef. Remove from skillet but keep warm. If the oil is excessive, remove all but 1 tablespoon.
Add onions and green bell pepper to skillet. Cook, stirring often, over medium-high heat for about 2 minutes.
Return beef to skillet. Add seasonings and water. Bring to a boil and reduce heat to medium-low. Simmer for about 20 minutes or until liquid has evaporated.
Stir in 1 cup cheese and sour cream until blended. Top with additional cheese and remove from heat.
Once cheese has melted, add additional toppings such as diced tomato, diced avocado, chopped cilantro, and sliced black olives.